This invention relates to the grinding of hydraulic cements to reduce the particle size thereof, and more particularly to the addition of certain chemical additives to such cements during the grinding thereof to improve the efficiency of the grinding operation.
In the processing of hydraulic cements, for example Portland cement, a grinding operation is generally employed either in the unprocessed or semi-processed state to reduce the cement to relatively small particle size. It is desirable in the grinding step to have as efficient an operation as possible, that is, to reduce the particular cement to the desired size using as little energy as possible. Toward this end, it is customary to add during the grinding operation chemicals known as "grinding aids" without having adverse effects on the properties of the ground product.
Many chemicals and chemical mixtures have been suggested for use as grinding aids for hydraulic cements such as Portland cement. Examples of such chemicals which have been successfully commercially applied include triethanolamine salts of acetic acid (U.S. Pat. No. 3,329,517 to Serafin) and triethanolamine salts of phenol (U.S. Pat. No. 3,607,326 to Serafin).
U.S. Pat. No. 2,203,809 (Bechtold) relates to substituted glycerols and their use as grinding aids. One such substituted glycerol is glycerol monoacetic ester.
U.S. Pat. No. 3,615,785 (Moorer et al) relates to grinding aids of a water-soluble polyol (e.g. propylene glycol) in combination with a water-soluble salt of an aliphatic acid (e.g. acetic acid). Such combinations reportedly produce synergistic results over either compound alone. Esterification of the polyol and acid is neither disclosed nor suggested.